1. Field of the Invention
The present invention relates to terpenoid compounds constituting derivatives of Saishin N described below, a process for preparing the derivatives and antiulcer agents containing the derivatives as an effective component. The present invention relates more particularly to a Saishin N derivative useful as a medicament for a peptic ulcer, a process for preparing the derivative and an antiulcer agent containing the derivative as an effective component.
The inventors of this invention had isolated and identified Saishin N of the below formula, i.e. 4,5-dihydroxy-2,6,6-trimethyl-2-cyclohepten-1-one, from a crude drug "Saishin" as an antiulcer material and developed a chemical method for preparing Saishin N and filed a Patent Application thereon (Japanese Unexamined Patent Publication No. 275640/1991), i.e. U.S. Ser. No. 659,754 filed Feb. 21, 1991, now U.S. Pat. No. 5,151,450, issued Sep. 29, 1992: ##STR2##
Saishin N has two hydroxy groups in the molecule and up to now it had been thought that there were no significant differences between the groups, because it was found to be difficult to react one of the hydroxy groups selectively, which has been an obstacle to the study of Saishin N derivatives.
2. Description of the Prior Art
Eichenberger et al, Helv. Chim. Acta, 63 (6), 1499-1519 (Ger.) 1980, discloses (per its English abstract) the photochemical isomerization of certain keto-enones, methanol addition thereto and photodecarbonylation thereof, no pertinent utility being indicated for these remote type compounds.